This study seeks to test the hypothesis that rapid oral administration of glucose induces insulin resistance that is significantly greater than if the same amount is given either slowly through the oral route or at any rate intravenously. Furthermore, we will examine the role of incretins, or gut derived hormones as a possible cause for this resistance. The protocol involves four outpatient visits and four different modalities of glucose administration (slow oral, fast oral, slow intravenous and fast intravenous) with frequent blood glucose, insulin, and incretin measurements.